IMTY 1 This KVM switch does not have an external power supply. This leads to faulty transfers as power is from the PC USB terminal. The voltage is not sufficient to drive the keyboard and the mouse.It stopped working about a week after I installed it. I am switching between a Mac and a Windows PC.It some times switches the Keyboard and the printer, but not the mouse. The video switching is the only thing that works.I have given up and now just unplug the USB devices and plug these into a Hub and use it manually.Returned this KVM Switch and purchased one with a 5V power input.Not recommend